JP4133897B2 - Optical receiver - Google Patents

Description

  The present invention relates to an optical receiver that converts an optical signal into an electrical signal.

  As an optical receiver that converts an optical signal into an electrical signal, in particular, an optical fiber link is widely used in general households for music, and an optical fiber that inputs and outputs an optical digital signal to a CD, MD, DVD player, amplifier, etc. A link light emitting / receiving device is used. In recent years, it has become widespread as an application for transmitting and transmitting music signals to portable devices such as notebook computers, mobile phones, MP3 players, etc., so the power consumption of optical fiber link devices has also been reduced to extend battery life. It has been demanded.

  Furthermore, optical fibers are excellent in light weight and noise resistance, and in-vehicle optical fiber links such as MOST (Media Oriented Systems Transport) and IDB1394 are in a practical stage, and low current consumption is required.

  7 and 8 show conventional optical receivers that detect the presence or absence of an input optical signal and switch between an operation mode and a standby mode.

  The conventional optical receiver of FIG. 7 is provided with a dedicated light receiving element PD1 for optical signal detection and an amplifier circuit AMP1, and the power supply circuit 103 is used for signal processing by the output signal of the comparator COMP1 for determining the output level of the AMP1. The power supplied to AMP2 and COMP2 is turned ON / OFF. That is, when an optical signal is incident, a reception circuit (optical signal detection circuit) 101 for detecting incident light switches the reception circuit (optical signal detection circuit) 102 for signal processing from the standby mode to the operation mode.

  FIG. 8 shows another conventional optical receiver with a shutdown function. When an optical signal enters a photodiode, a voltage drop occurs due to R1, and this voltage drop turns on MP1 and MP2 of P-channel MOSFETs. The receiving circuit is switched to the operation mode by supplying power to the amplifier circuit AMP1 and the waveform shaping circuit COMP2. In this case, there is a drawback that the photodiode cannot be used in a receiving circuit in which the anode of the photodiode is connected to GND.

Conventional literature includes the following.
JP 2002-280971 A (publication date September 27, 2002) JP 2000-078091 A (publication date March 14, 2000)

  However, in the configuration of FIG. 7, even when no optical signal is incident, the light detection amplifier circuits AMP1 and COPM1 need to be operated, so that a current flows during standby.

  In addition, since it is necessary to separately prepare a photodiode for detecting an optical signal, the number of parts is increased, and in the case of OPIC (optical IC), there is a disadvantage that a chip area is increased.

  The present invention has been made in view of the above problems, and an object of the present invention is to realize an optical receiver capable of reducing the current flowing during standby.

In order to solve the above-described problems, an optical receiver according to the present invention is an optical receiver including a signal processing circuit that outputs and processes data received by a light receiving element, and a current signal generated by the light receiving element is reduced. a voltage conversion circuit, said current - - a filter circuit which performs both the separation of the separation and the high-frequency current of frequency current, a current of converting only the low-frequency current separated by the filter circuit to the voltage converted by the voltage conversion circuit A comparator that outputs an instruction to switch the signal processing circuit to an operation mode when the converted voltage is greater than the reference value, and based on the instruction of the comparator, And a bias circuit for starting the signal processing circuit, and the high-frequency current is supplied to the signal processing circuit .

  With the above configuration, the low frequency current and the high frequency current of the current signal generated in the light receiving element are separated, the low frequency current is converted into a voltage, and the signal processing circuit is activated by the output. If the result of converting the low frequency current to voltage is below a certain level, the signal processing circuit is shifted to the standby mode. Therefore, the signal processing circuit can be activated based on the magnitude of the low-frequency current of the current signal generated in the light receiving element, and unlike the conventional case, a current is always supplied to the circuit for detecting light in the standby mode. There is no need to have a configuration to be kept. Therefore, there is an effect that it is possible to realize an optical receiver and an optical receiver for an optical fiber link that can reduce a current flowing during standby.

  Further, with the above configuration, the presence or absence of light is determined based on the fact that light is received by the light receiving element for signal processing. Therefore, it is possible to eliminate the need for separately preparing an element for detecting light in the standby mode, that is, a photodiode for detecting an optical signal. Therefore, in the case of OPIC (Optical IC), an increase in the chip area can be suppressed.

In addition to the above configuration, the optical receiver according to the present invention includes a resistor and a capacitor connected to the light receiving element in the filter circuit, and the light receiving element is connected to the signal processing circuit via the capacitor. are connected, between the said capacitor and the signal processing circuit, it is characterized in that grounding switch element is switched by the comparator to ground in the standby mode is connected.

  With the above configuration, in the filter circuit, a resistor and a capacitor are connected to the light receiving element. Therefore, in addition to the effect of the above configuration, the low frequency current and the high frequency current of the current signal generated in the light receiving element can be separated with a simple configuration.

  Further, in the optical receiver according to the present invention, in addition to the above-described configuration, the signal processing circuit includes a first-stage current-voltage conversion circuit and a subsequent-stage current-voltage conversion circuit. The input impedance is low when the current-voltage conversion circuit in the first stage of the circuit is started.

  With the above configuration, the input impedance is lowered when the current-voltage conversion circuit in the first stage of the signal processing circuit is started. Therefore, even in the operation mode, the capacitor is grounded as in the standby mode. Therefore, in addition to the effect of the above configuration, there is an effect that a change in characteristics such as a cut-off frequency of the filter circuit can be reduced in the standby mode and the operation mode.

  In addition to the above configuration, the optical receiver according to the present invention is characterized in that a compression circuit is connected in parallel to the resistor connected to the light receiving element.

  With the above configuration, the compression circuit is connected in parallel to the resistor connected to the light receiving element.

  Therefore, even when a large amount of light signal is input, it is possible to prevent the voltage drop of the resistor connected to the light receiving element from increasing. Therefore, in addition to the effect of the above configuration, there is an effect that it is possible to prevent a decrease in speed due to a decrease in the bias voltage of the light receiving element and an increase in parasitic capacitance of the light receiving element.

  In addition to the above configuration, the optical receiver according to the present invention is characterized in that a bidirectional compression circuit is connected in parallel to the feedback resistor of the current-voltage conversion circuit in the first stage of the signal processing circuit. .

  With the above configuration, the bidirectional compression circuit is connected in parallel to the feedback resistor of the current-voltage conversion circuit in the first stage of the signal processing circuit.

  Therefore, in addition to the effect of the above configuration, there is an effect that an increase in output pulse width distortion at the time of inputting a large amount of light signal can be suppressed.

  In addition, with the above configuration, compression is performed in both directions. Therefore, it is possible to make the threshold come just at 50% of the signal. Therefore, in addition to the effect of the above configuration, the output pulse width distortion can be reduced.

An optical receiver according to the present invention includes, in addition to the above configuration, a current mirror that amplifies a current connected to a resistor connected to the light receiving element in the current-voltage conversion circuit, and the current mirror. current and resistance for voltage conversion for converting the voltage provided to by said comparator, and a Schmitt trigger circuit the voltage across the resistor for the voltage conversion is input, connected in series to the Schmitt trigger circuit It is characterized by comprising an inverter circuit .

  With the above configuration, a current mirror is used to amplify the current, convert the voltage with a resistor, and a comparator is connected. When the voltage across the resistor exceeds a certain voltage, the signal processing circuit operates with respect to the bias circuit. Instruct to switch to mode. Therefore, in addition to the effect of the above configuration, the signal processing circuit can be switched to the operation mode according to the presence or absence of the optical signal with a simple configuration.

  In addition to the above configuration, the optical receiver according to the present invention is characterized in that the output of the comparator is taken out as a status signal.

  With the above configuration, the output of the comparator is taken out as a status signal. Therefore, in addition to the effect of the above configuration, processing such as delaying the output of the comparator can be added as appropriate, and the versatility can be improved. In addition to the above-described configuration, the optical receiver according to the present invention takes out the output of the comparator as the status signal through a delay circuit having a time constant longer than the time during which the signal processing circuit is stabilized. It is characterized by that.

  With the above configuration, the output of the comparator is taken out as a status signal through the delay circuit having a time constant longer than the time during which the signal processing circuit is stabilized. Therefore, after the signal processing circuit is sufficiently stabilized, the system can be further stabilized by outputting the status signal as a signal for starting the microcomputer (controller) connected to the subsequent stage.

In addition to the above-described configuration, the optical receiver according to the present invention is connected to the output terminal of the signal processing circuit, and does the duty ratio of the output of the signal processing circuit match a preset duty ratio? If it is detected and matched, a duty ratio detection circuit that outputs a first level detection signal is connected to the output terminal of the signal processing circuit, and the output frequency of the signal processing circuit is preset. The frequency detection circuit that detects whether or not the frequency matches and outputs a first level detection signal, and is connected between the output terminal of the signal processing circuit and the signal output terminal of the optical receiver. An output control circuit for guiding the output of the signal processing circuit to a signal output terminal of the optical receiver based on the first level detection signals of the duty ratio detection circuit and the frequency detection circuit; The duty ratio set in advance in the duty ratio detection circuit and the frequency set in advance in the frequency detection circuit correspond to the optical signal input to the light receiving element, respectively. The duty ratio and the frequency of the output of the signal processing circuit in the case where the optical signal is output from the optical transmitter .

With the above configuration, between the output and the signal output terminal of the signal processing circuit, an output control circuit is provided, and the duty ratio and the frequency of the output of the signal processing circuit, "input optical signals, set Of the signal processing circuit when the optical signal input to the light receiving element is an optical signal output by an optical transmitter corresponding to the optical receiver . only the output control circuit when the output is a duty ratio and frequency "is turned on, the signal of the signal processing circuit to the signal output terminal is output. Therefore, the output signal can be output from the signal output terminal only when the input optical signal is a set desired correct modulation signal. Therefore, in addition to the effect of the above configuration, an unnecessary output can be omitted and the efficiency can be improved.

Further, the optical receiver according to the present invention, wherein in addition to the above structure, by multistage connection of a resistor and a current mirror that, with a monitor terminal for monitoring the intensity of light incident on the light receiving element It is said.

  With the above configuration, the intensity of the optical signal incident on the light receiving element is monitored. Therefore, in addition to the effect of the above configuration, processing such as delaying the output of the comparator can be added as appropriate, and the versatility can be improved.

  As described above, the optical receiver according to the present invention includes a filter circuit that separates a low frequency current and a high frequency current of a current signal generated by the light receiving element, and a current-voltage conversion that converts the low frequency current into a voltage. Circuit and a bias circuit that activates the signal processing circuit according to the output of the current-voltage conversion circuit, the signal processing circuit is activated based on the magnitude of the low-frequency current of the current signal generated by the light receiving element. Unlike the prior art, it is not necessary to have a configuration in which a current is always supplied to a circuit for detecting light in the standby mode. Therefore, there is an effect that it is possible to realize an optical receiver and an optical receiver for an optical fiber link that can reduce a current flowing during standby.

  In addition, this eliminates the need to separately prepare an element for detecting light in the standby mode, that is, an optical signal detection photodiode. Therefore, in the case of OPIC (Optical IC), an increase in the chip area can be suppressed.

[Embodiment 1]
FIG. 1 is a block diagram of an optical receiver 1 showing this embodiment. The light receiving element 11 converts an optical signal transmitted from the outside through a fiber cable or the like into a current signal. The current signal of the light receiving element is separated by a low frequency / high frequency current separation filter circuit (filter circuit) 12 into a low frequency current component close to the DC component of the current signal and a high frequency current component including a data string.

  The low frequency current component is subjected to current-voltage conversion by the current-voltage conversion circuit 13, input to the comparator 14, and input to the bias circuit 15.

  The current component of the light receiving element will be described in a little more detail with reference to FIG. The light receiving element current waveform in FIG. 2 is obtained when a biphase mark-modulated optical signal used in an optical fiber link for digital audio, an in-vehicle MOST, or the like enters the light receiving element. The waveform in FIG. 2 corresponds to the case where the data string is “1001101011”.

  This light receiving element current waveform is separated into a low-frequency current component and a high-frequency current component using a filter circuit. That is, the binary waveform of the high level and the low (zero) level is originally a binary waveform high-frequency current component (current waveform B) having the same absolute value but the opposite polarity. Thus, the DC current component (low frequency current component) (current waveform A) is subtracted. Therefore, it can be seen that this light receiving element current waveform is the sum of the current waveform A and the current waveform B. The current waveform A is a low-frequency current component, and becomes a DC current component when the data string is sufficiently long. The current waveform B is a high-frequency current component and is a signal including data string information.

  When the optical signal is incident on the light receiving element and the light receiving element current waveform as shown in FIG. 2 is generated, the low-frequency current corresponding to the current waveform A is converted into a voltage by the current-voltage conversion circuit 13 as described above. When the voltage exceeds a certain level, the output of the comparator 14 is inverted, and the bias circuit 15 is switched from the standby mode to the operation mode. As a result, a bias current is supplied to the pre-stage amplifier 16, the post-stage amplifier 17, and the comparator 18, and the signal processing circuit 20 starts operating.

  On the other hand, the high-frequency current including the data string is subjected to current-voltage conversion by the pre-stage amplifier 16, further amplified by the post-stage amplifier 17, shaped by the comparator 18, and output as a digital signal to the signal output terminal 19.

  When the optical signal does not come to the light receiving element, the light receiving element current waveform as shown in FIG. Then, the result of dividing it into a low-frequency current component and a high-frequency current component using a filter circuit is both “always zero”. Therefore, when the low-frequency current component is converted into a voltage by the current-voltage conversion circuit 13, the voltage becomes “always zero” and does not satisfy the condition of “above a certain level” described above. Then, since the output of the comparator 14 is not inverted, the bias circuit 15 is switched from the operation mode to the standby mode. As a result, the bias current is not supplied to the pre-stage amplifier 16, the post-stage amplifier 17, and the comparator 18, and the signal processing circuit 20 stops operating and enters a standby mode. Thus, the bias circuit 15 has a shutdown function for stopping the bias current supplied to each signal processing circuit block in the standby mode. That is, in the standby mode, no current flows through a portion that outputs a signal (high-frequency current component) corresponding to the data string. More precisely, the leakage current of the device can be suppressed.

  In this way, by detecting the low frequency current component of the signal to be transmitted, the operation mode is set when the optical signal is incident on the light receiving element, and the battery operation is performed by switching to the standby mode when there is no optical signal input. A suitable low current consumption optical receiver can be realized. The light receiving element and the optical receiver can be monolithically formed on one chip as an OPIC, which is advantageous for downsizing the receiver.

[Embodiment 2]
As shown in FIG. 3, the modulated optical signal is converted into a current signal by the light receiving element PD1. When the optical receiver is on standby, the gate voltage of the N-channel MOSFET (MN1) is at a high level. When MN1 is turned on, one electrode of the capacitor C1 is grounded to the GND level. A low-frequency current component of the current flowing through the light receiving element flows through the resistor R1 and a high-frequency current component flows through the capacitor C1 by the filter circuit including the resistor R1 and the capacitor C1 grounded when the MN1 is turned on. More specifically, the current flowing through the resistor R1 is
fc = 1 / {2π · (R1 + Vt / IDC_PD) · C1}
(Where Vt: k · T / q
k: Boltzmann constant T: Absolute temperature q: Elementary charge IDC_PD: DC current component flowing in the light receiving element PD1. )
The current signal passed through the low-pass filter having a cutoff frequency of 1 and the current flowing through the capacitor C1 becomes the current signal passed through the high-pass filter having the cutoff frequency fc.

  Biphase-modulated signals often used in optical fiber communications such as optical fiber links for digital audio and MOST standards for in-vehicle fibers have a duty ratio of 50%. And AC current components (50 MHz and 25 MHz AC current components in the case of a 25 Mbps biphase signal).

  The direction of the current of the DC current flowing through the resistor R1 is changed by a current mirror composed of the PNP transistors QP1 and QP2, and is converted into a voltage by the resistor R3.

  When the incident light is weak (when the voltage drop due to R1 is low), the bias voltage VR of the light receiving element PD1 is Vcc-Vbe (for example, when Vcc = 5V, if Vbe of QP1 is 0.6V, VR = 4.4V) Therefore, when the light receiving element is a photodiode, the parasitic capacitance is reduced, which is advantageous for speeding up and reducing noise of the optical receiver.

  Alternatively, the current area may be amplified N times with a current mirror, with the emitter area ratio of QP1 and QP2 being 1: N. When the voltage across the resistor R3 exceeds the threshold value of the comparator COMP1, the output of the comparator COMP1 changes from high level to low level, and the bias circuit 15 is activated. When the bias circuit 15 is activated, a bias current is supplied to the signal processing circuit 20 AMP1, AMP2, AMP3, COMP2, and the signal processing circuit 20 is activated (changes to the operation mode). Further, when the gate voltage of the N-channel MOSFET (MN1) becomes a low level, MN1 is turned OFF, whereby the AC current component including the modulation signal flowing through the capacitor C1 is composed of AMP1, Rf1, and Cf1. It is input to a current-voltage conversion circuit which is a current-voltage conversion amplifier.

  In addition, when AMP1 is activated, the input impedance of the current-voltage conversion amplifier becomes low. Therefore, even if MN1 is turned off, the capacitor C1 is grounded, and the filter circuit is configured by the resistor R1 and the capacitor C1. Has an advantage that the change in characteristics such as the cut-off frequency is small between the standby mode and the operation mode.

  Further, the light receiving element PD2 is a dummy light receiving element having the same area as the light receiving element PD1, and is effective in removing in-phase components of electromagnetic noise and power line noise by shielding light from the cathode electrode. is there. The same number of elements (R2 = R1, C2 = C1, MN2 = MN1, AMP2 = AMP1, Rf2 = Rf1, Cf2 = Cf1) connected to the light receiving element PD1 are also connected to the dummy light receiving element PD2. Thus, an optical receiver that is resistant to power supply noise and disturbance noise can be realized.

  The signal converted into a voltage by AMP1 is input to AMP3 via a capacitor C3. The resistors Rref1 and Rref2 are connected to the input of the amplifier circuit AMP3 via the constant voltage source Vref, and are resistors for determining the operating point of the input of the AMP3. The signal is amplified by AMP3, shaped by the comparator COMP2, and output as a digital signal to the OUT terminal.

  In addition, there is a time lag between the moment when the output of COMP1 changes from the high level to the low level until the bias circuit and the signal processing circuit are activated. Therefore, a STATUS terminal with a delay circuit 25 is provided at the output of COMP1, the time constant of the delay circuit 25 is set to be longer than the time required for the output of the signal processing circuit to settle, and output after an optical signal is input When STATUS is sufficiently stable, the STATUS terminal is inverted. Thereby, it can also be used as a start signal for a microcomputer or the like connected to the subsequent stage.

  Further, as shown in parentheses in FIG. 3, the comparator COMP1 has a two-stage connection between a CMOS Schmitt trigger and an inverter that allows current to flow only when the output is inverted, so that light when no optical signal is incident can be obtained. It is also possible to make the current consumption of the receiver almost zero.

[Embodiment 3]
As shown in FIG. 4, in addition to the configuration of FIG. 3, the low frequency current flowing through the light receiving element PD1 is amplified by a current mirror composed of PNP transistors QP1 and QP4, converted into a voltage by a resistor Rmon, and passed through a buffer B. Output to the MONITOR terminal. Thereby, it is possible to monitor the intensity of the optical signal incident on the light receiving element PD1. In addition, it is possible to connect the current mirror in multiple stages, and in combination with the window comparator, the receiver can be set to the operation mode only when the optical signal incident on the light receiving element is within a certain range.

[Embodiment 4]
As shown in FIG. 5, in addition to the configuration of FIG. 3, the light receiving element is provided with a compression circuit including a diode D1 and a resistor R4. Thereby, even when a light signal with a large amount of light is input, it is possible to prevent the voltage drop of the resistor R1 from increasing, and thus it is possible to prevent the bias voltage of the light receiving element PD1 from decreasing. Normally, the resistor R4 is set to about 1/10 of the resistor R1.

  In addition, by providing a compression circuit composed of Df1, Df2, Rf3, and Cf3 in a current-voltage conversion amplifier composed of AMP1, Rf1, and Cf1, an increase in output pulse width distortion when a large amount of light signal is input Can be suppressed.

  In particular, in the MOST standard for in-vehicle fibers, the light input range is -2 dBm to -23 dBm, which is wider than the optical input range of conventional optical fiber links for digital audio, -14 dBm to -24 dBm. Is effective because the dynamic range is expanded.

  In addition, since the input is AC-coupled by C1, a bi-phase modulated signal having a duty ratio of 50% is compressed in both directions by Df1 and Df2, so that the threshold value is exactly 50% of the signal. Therefore, there is an advantage that the pulse width distortion of the output is reduced.

[Embodiment 5]
As shown in FIG. 6, an output control circuit 27 is provided between the comparator COMP2 configured as shown in FIG. 3 and the output OUT terminal to control whether the output is output or not, and the duty ratio of the output of the comparator COMP2 is detected. A duty ratio detection circuit 28 for detecting the output of the comparator COMP2, and a frequency detection circuit 29 for detecting the frequency of the output of the comparator COMP2. A signal obtained by ANDing the outputs of the two detection circuits (28 and 29) and the activation signal of the bias circuit 15 through the delay circuit 25 with AND1 is output as a STATUS terminal, and this is output as an output control circuit 27. Control signal.

  In the two detection circuits (28, 29), the duty ratio and the frequency of the output of the comparator COMP2 when the input optical signal is a desired desired correct modulation signal are stored and set, respectively. Yes. The two detection circuits (28, 29) detect whether or not the duty ratio and frequency of the output of the input comparator COMP2 match the set duty ratio and frequency, and only when the two match, The two detection circuits (28, 29) determine that the input optical signal is a set modulation signal, and output a true (high) signal.

  Thereby, it is possible to output an output signal from the signal output terminal only when the input optical signal is a set modulation signal.

  Thus, the present invention activates the signal processing circuit based on the magnitude of the low frequency current of the current signal generated in the light receiving element. That is, the present invention detects light when no optical signal is incident by detecting a DC current component (low frequency current component) of the light receiving element and switching the reception circuit between a shutdown mode and an operation mode as a standby mode. It is possible to reduce the consumption current of the receiver to almost zero (about the leakage current of the device).

  Further, it is possible to realize an optical receiver that is advantageous in reducing power consumption without requiring an external shutdown control signal.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  It can also be applied to applications such as an optical receiver that can reduce the current flowing during standby.

It is a block diagram which shows the example of 1 structure of the optical receiver which concerns on this invention. It is a figure which shows the photocurrent waveform of a light receiving element. It is a circuit diagram which shows one structural example of the optical receiver which concerns on this invention. It is a circuit diagram which shows one structural example of the optical receiver which concerns on this invention. It is a circuit diagram which shows one structural example of the optical receiver which concerns on this invention. It is a circuit diagram which shows one structural example of the optical receiver which concerns on this invention. It is a circuit diagram which shows one structural example of the conventional optical receiver. It is a circuit diagram which shows one structural example of the conventional optical receiver.

Explanation of symbols

1 Optical receiver 11 Light receiving element 12 Low frequency / high frequency current separation filter circuit (filter circuit)
13 Current-Voltage Conversion Circuit 14 Comparator 15 Bias Circuit 16 Preamplifier 17 Subsequent Amplifier 18 Comparator 19 Signal Output Terminal 20 Signal Processing Circuit 25 Delay Circuit 27 Output Control Circuit 28 Duty Ratio Detection Circuit 29 Frequency Detection Circuit

Claims (10)

In an optical receiver including a signal processing circuit that outputs and processes data received by a light receiving element,
A filter circuit that performs both low frequency current separation and high frequency current separation of the current signal generated in the light receiving element;
A current-voltage conversion circuit that converts only the low-frequency current separated by the filter circuit into a voltage;
A comparator that compares the voltage converted by the current-voltage conversion circuit with a reference value and outputs an instruction to switch the signal processing circuit to an operation mode when the converted voltage is greater than the reference value. When,
A bias circuit for starting the signal processing circuit based on an instruction from the comparator ;
An optical receiver characterized in that the high-frequency current is supplied to the signal processing circuit . In the above filter circuit,
The above light-receiving element is connected to the resistor and the capacitance, the light receiving element through the capacitor is connected to the signal processing circuit, between the capacitor and the signal processing circuit is grounded to the standby mode The optical receiver according to claim 1, wherein a grounding switch element switched by the comparator is connected. The signal processing circuit has a first-stage current-voltage conversion circuit and a subsequent-stage current-voltage conversion circuit,
3. The optical receiver according to claim 2, wherein the input impedance becomes low when the current-voltage conversion circuit in the first stage of the signal processing circuit is started.   The optical receiver according to claim 3, wherein a compression circuit is connected in parallel to the resistor connected to the light receiving element.   4. The optical receiver according to claim 3, wherein a bidirectional compression circuit is connected in parallel with the feedback resistor of the first-stage current-voltage conversion circuit of the signal processing circuit. In the current-voltage conversion circuit,
A current mirror connected to a resistor connected to the light receiving element and amplifying a current;
Current and resistance for voltage conversion for converting the voltage provided to by the current mirror,
The comparator comprises a Schmitt trigger circuit to which a voltage across the voltage conversion resistor is input, and an inverter circuit connected in series to the Schmitt trigger circuit. The optical receiver as described in any one of .   7. The optical receiver according to claim 6, wherein an output of the comparator is taken out as a status signal.   8. The optical receiver according to claim 7, wherein an output of the comparator is taken out as the status signal through a delay circuit having a time constant longer than a time during which the signal processing circuit is stabilized. Connected to the output terminal of the signal processing circuit, detects whether the duty ratio of the output of the signal processing circuit matches a preset duty ratio, and outputs a first level detection signal if they match A duty ratio detection circuit for
A frequency that is connected to the output terminal of the signal processing circuit, detects whether the output frequency of the signal processing circuit matches a preset frequency, and outputs a first level detection signal if the frequency matches. A detection circuit;
Connected between the output terminal of the signal processing circuit and the signal output terminal of the optical receiver, and based on the first level detection signals of the duty ratio detection circuit and the frequency detection circuit, An output control circuit for guiding the output of the signal processing circuit to a signal output terminal;
The duty ratio set in advance in the duty ratio detection circuit and the frequency set in advance in the frequency detection circuit are respectively determined by the optical transmitter in which the optical signal input to the light receiving element corresponds to the optical receiver. 8. The optical receiver according to claim 7, wherein the optical receiver has a duty ratio and a frequency of an output of the signal processing circuit when the optical signal is in an output state . By multistage connection of a current mirror resistor and the light receiver according to claim 6, characterized in that it comprises a monitor terminal for monitoring the intensity of light incident on the light receiving element.

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